1. Field of Invention
The present invention relates to a filtering unit.
2. Related Prior Art
As disclosed in U.S. Pat. No. 7,396,462, a filtering unit 100 includes a fluid-collecting tube 7 inserted through alternately arranged positioning rings 2 (2′) and membranes 5. The fluid-collecting tube 7 defines a fluid channel 70 and apertures 71 in communication of fluid with the fluid channel 70.
Each of the positioning rings 2 (2′) includes an annular body 21 (21′) sleeved around the fluid-collecting tube and formed with annularly displaced arched cutouts 23 (23′) around the fluid-collecting tube. Each of the arched cutouts 23 (23′) includes opposite first and second ends 231 and 232 (231′ and 232′). The annular body 21 (21′) of each of the positioning rings 2 (2′) includes a plurality of first engaging members 24 (24′) and a plurality of second engaging members 25 (25′). Each of the first engaging members 24 (24′) is located adjacent to the first end 231 (231′) of a respective one of the arched cutouts 23 (23′). Each of the second engaging members 25 (25′) is located adjacent to the second end 232 (232′) of a respective one of the arched cutouts 23 (23′).
The rings 21, 21′ of each adjacent pair of the positioning rings 2, 2′ are coupled to each other and are rotatable relative to each other between a first relative position and a second relative position offset from the first relative position.
The first engaging members 24 of the ring 21 of each adjacent pair of the positioning rings 10, 10′ are disengaged from the second engaging members 25′ of the ring 21′ of each adjacent pair of the positioning rings 10, 10′ when the rings 11, 11′ of each adjacent pair of the positioning rings 10, 10′ are located in the first relative position. The first engaging members 24 of the ring 21 of each adjacent pair of the positioning rings 10, 10′ are engaged with the second engaging members 25′ of the ring 21′ of each adjacent pair of the positioning rings 10, 10′ when the rings 11, 11′ of each adjacent pair of the positioning rings 10, 10′ are located in the second relative position.
The annular body 11 (11′) of each of the positioning rings 10 (10′) includes upper and lower surfaces 211 and 212 (211′ and 212′), and is further formed with upper and lower annular recesses 28 (28′) indented inwardly and respectively from the upper and lower surfaces 211 and 212 (211′ and 212′). Upper and lower seals 3 are respectively located in the upper and lower annular recesses 28 (28′) in the annular body 11 (11′) of each of the positioning rings 10 (10′) and are respectively in sealing contact with an adjacent pair of the membranes 5.
The seals 3 provide good sealing between the positioning rings 10 (10′) and the membranes 5. However, each of the seals 3 is subject to a friction-based torque from a related one of the positioning rings 10 (10′) and is subject to an opposite friction-based torque from a related one of the membranes 5 when the positioning ring 2 (2′) is spun relative to the membrane 5 during the assembly. The difference between the values of the friction-based torques spins the seal 3 and would sometimes remove the seal 3 from the annular recess 28 (28′).
The present invention is therefore intended to obviate or at least alleviate the problems encountered in prior art.